Question

The well-cited RIP Hash rocket post would seem to imply the Hash Rocket syntax (:foo => "bar") is deprecated in favor of the new-to-Ruby JSON-style hash (foo: "bar"), but I can’t find any definitive reference stating the Hash Rocket form is actually deprecated/unadvised as of Ruby 1.9.

Answer 1

The author of that blog post is being overly dramatic and foolish, the => is still quite necessary. In particular:

1. You must use the rocket for symbols that are not valid labels: :$set => x is valid but $set: x is not. In Ruby 2.2+ you can get around this problem with quotes: '$set': x will do The Right Thing.

2. You must use the rocket if you use keys in your Hashes that aren’t symbols, such as strings, integers or constants. For example, 's' => x is valid but 's': x is something completely different.

You can kludge around the above in the obvious manner of course:

h = { }
h[:'where.is'] = 'pancakes house?'
# etc.

but that’s just ugly and unnecessary.

The rocket isn’t going anywhere without crippling Ruby’s Hashes.